St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1887-05-07
COLLIERY EXPLOSIONS.
Efforts Which Have Been Made
to Prevent Them.


tloc0 To SAFER Met0O0e O9
Explosions.
The atmosphere of every coal-mine
probably contains more or less marsh
gas. although in some the amount is SO
very small that the air within them
could never become explosive under or
dinary conditions Of working. There
is no doubt that gas frequently escapes
detection owing to the imperfection Of
the means employed for its recognition.
II present in certain proportions the
marsh gas is revealed by the elOnga-
ton of the flame of the safety-lamp, or
by the appearance of what is
known as a leap" upon the flame.
An experienced eye can determine pref
ty accurately the relative amount of
the firc-iamp from the size and character
of the cap upon q properly trimmed
flame; but the test altogether fails when
the proportion of gas falls below two
per cent. This amount, small as it may
seem, may, under certain circum-
stances. prove highly dangerous. The
mine-manager and the ''firemen" re-
quire to use some more delicate method
Of detecting small quantities of fire
damp than that usually employed. For
tunately such methods are not unknown.
Mr.. Livcing has devised very ingeni-
Gus indicator, by which the existence
Of marsh gas can be detected and its
amount estimated even when the guam
tity is as low rs a quarter per cent
Two precisely similar pieces of thin
platinum wire are simultaneously
heated to bright redness by the action
of small magneto-electric machine
worked by hand. One of the wires is
contained in small tube filled with pure
air; the other can be surrounded at will.
and in a minute or two. with air
from any part Of the mine. II fire.
damp is present it burns round the hot
wire. which is thereby increased in
temperature and emits more brilliant
light BY comparing the intensities of
the light emitted by the two wires by
the aid of very simple photometric
arrangement the percentage amount Of
fire-damp present may be at once de-
termined. The apparatus is portable
and easily worked, and is well adapted
for use under ground.
Seventy years have elapsed since Sir
Humphrey Davy invented the safety
lamp which is associated with his name.
1t is almost impossible to overestimate
the influence of that invention in the
development Of coal-mining- lin the de-
velopment, indeed. of our national
prosperity. It has unquestionably
saved thousands Of lives, and has en-
abled millions Of tons of coal to be
raised which. without it, could not pos
sibly have been won.
II is related that when Mr.. Buddle,
whose name is well known in the
history Of coal-mining for the
improvements he introduced into
the system Of vcntilating collieries,
took down one of the first Davy lamps
into fiery pit and beheld the fire-damp
''cap" playing round the light and ap-
parently imprisoned within the wire
gauze cylinder. he exclaimed exult-
ingly: AT last we have subdued this
Not year passes, however, without
the monster showing us that he is |
still very far from subjection; and.
strange to say. the Davy lamp itself |
and the very system of ventilation |
which we owe to Mr.. Buddle, as de-
veloped in these later times. have con-
spired to aid the monster in his work
Of havoc and disaster.
How this has come about NAV be
told in very few words. When the
lamp was first introduced the ventilat-
ing currents in mines seldom exceeded a
velocity of three hundred feet per
minute in the air-ways. and they were
usually very feeble in the working
places. Nowadays the enormous fans
Ind other mechanical ventilators which
IRE employed cause the air to travel at
selocities approaching two thousand
'eet per minute in the air-ways. and cur.
,ents of more than four hundred feet per
minute are not unfrequently met with
It the working places. Under these
conditions the Davy lamp and, in a
esser degree, two other well-known ,
orms Of safety lamp-the Clanny and ,
he Stephenson lamps-become abso-
utely unsafe in an explosive atmos- ,
here. Indeed. the ordinary Davv
amp will ignite gas outside it If ex-
,osed to an explosive current travelling ,
4 less than four hundred feet per min ,
10 4
The Royal Commissioners. as far back I
q 1880. directed the attention of the I
lone Secretary to the fact ''that the {
Employment Of the ordinary Davy lamp
,ithout shield Of metal or Of glass. in Z
a explosive mixture. when the air 9
urrents exceed six feet per second, is 1
ttended with risk # accident almost I